Those skilled in the hydrocarbon recovery industry recognize the increasing significance of jet pumps in recovering formation fluids. The potential for jet pumps for pumping formation fluids from a well to the surface is enhanced by its relatively low cost compared to systems which use a reciprocating or rotating rod string to pump fluids to the surface. For many applications, jet pumps are preferable compared to electric submersible pumps, which are frequently not considered reliable for use in producing high solid content formation fluids.
Various problems have limited the success of jet pumps in the hydrocarbon industry. More particularly, manufacturers have not recognized the components of jet pumps which should be better protected in order to enhance the pump life and reliability. Many jet pump components are subjected to a unique combination of conditions which enhance corrosion and/or abrasive wear. Jet pumps have been manufactured for decades, but the prior art has not recognized the fluid flow characteristics of jet pumps which have limited their efficiency and reliability.
A downhole jet pump which was retrievable by reverse flow is disclosed in U.S. Pat. No. 5,083,609. Further improvements to a downhole jet pump are disclosed in U.S. Pat. No. 5,372,190. The '190 patent discloses a pump with a retrievable nozzle and mixing tube. The mixing tube may be pressed within two carriers by a chemical adhesive.
U.S. Pat. No. 4,603,735 discloses another type of jet pump having a reverse up flow. U.S. Pat. No. 4,790,376 discloses a pump wherein power fluid may be injected down the annulus and produced up the tubing string, or power fluid may be injected down the tubing string and produced up the annulus. U.S. Pat. No. 5,055,022 discloses a type of downhole jet pump with a retrievable nozzle assembly. U.S. Pat. No. 4,658,893 also discloses a downhole jet pump with a reverse flow ejection nozzle.
The disadvantages of the prior art are overcome by the present invention, and an improved jet pump is hereinafter disclosed.